The Stille Reaction of 1,1-Dibromo-1-alkenes: Preparation of Trisubstituted Alkenes and Internal Alkynes

Publisher Website
Google Scholar
Abstract
The Stille reaction of 1,1-dibromo-1-alkenes 1 with aryl- and vinylstannanes produces different products depending on the reaction conditions. When the reaction is run in toluene or 1,4-dioxane with tris(2-furyl)phosphine (TFP) as the ligand, (Z)-bromoalkenes 2 are obtained stereospecifically in good to excellent yields with most substrates. However, 2-aryl-1,1-dibromo-1-alkenes (1e,1g) having an electron-donating methoxy group in the para- or ortho- position give poor yields. This method has been applied to the one-pot syntheses of stereospecifically trisubstituted alkenes 5. When the Stille reaction is conducted in a highly dipolar solvent (DMF), monobromides 2 and/or internal alkynes 4 are the products. The less reactive phenylstannane favors the formation of alkynes 4, regardless of which ligand is used. More reactive organostannanes (vinyl, furyl) require a very electron rich ligand, tris(4-methoxyphenyl)phosphine, for the formation of alkynes 4. This new method for internal alkyne preparation is general, requires very mild reaction conditions, and gives high yields.

This publication has 28 references indexed in Scilit: